1. Field of the Invention
The present invention relates to a display panel device including a flat display panel and a front sheet that is glued on the display panel.
2. Description of the Prior Art
Technology development of a plasma display panel (PDP) that is a self-luminous device is directed to a large screen for providing more powerful display. One of the important tasks for a large screen is weight reduction of the panel.
In general, a display device including a plasma display panel has a filter plate having a base of a tempered glass. This filter plate is arranged in front of the plasma display panel with air gap. The filter plate has various functions of adjusting a display color optically, preventing reflection of external light, shielding electromagnetic waves, and shielding near infrared rays concerning displaying operation and a function of protecting the plasma display panel mechanically. However, the filter plate is not suitable for a large screen of the plasma display panel because it has a large weight.
In order to reduce a weight of the display device, another structure is proposed in which a filter film having a base of a resin film is glued directly on the front face of the plasma display panel instead of the filter plate. Japanese unexamined patent publication No. 2001-343898 discloses a front face filter that includes a transparent conductive film for reducing electromagnetic wave radiation noise and a anti-reflection film that is glued on the front side of the transparent conductive film. A plane size of the anti-reflection film is smaller than a plane size of the transparent conductive film, and the peripheral portion of the transparent conductive film is not covered with the anti-reflection film. The peripheral portion of the transparent conductive film is connected to a conductive housing, so that electromagnetic wave energy flows from the transparent conductive film to the housing in the form of current and disappears.
It is difficult to realize plural functions by a single layer necessary for the front face of the display panel. The functions include improving optical characteristics of the screen, shielding EMI (Electro Magnetic Interference) and protecting the screen mechanically. In order to provide a display panel device having plural functions required by a specification, it is necessary to glue a multi-layered film on the front face of the display panel. In addition, it is also important to provide it at low cost.